1. Field of the Invention
The present invention relates to a measurement device, and in particular, relates to a measurement device used for electrically measuring and checking an electrical circuit.
2. Description of the Related Art
For the purpose of operation verification tests or failure analysis, an active probe is used to measure internal voltages in integrated circuits of, for example, display devices typified by LSIs, LCDs, and OLEDs. An FET probe, which is a typical example of an active probe, includes a field effect transistor (FET) that is an active element and a passive element, and further, a power source is used. With an active probe having such a structure, higher input impedance (e.g., 1 MΩ or greater) and lower input capacitance (e.g., 1 pF or less) than a passive probe constituted by C (capacitor) and R (resistor) can be achieved, and a waveform can be observed while a device under test (DUT) is not adversely affected as much as possible.
The leakage current of an active probe is low. For example, an active probe with leakage current of approximately 10−14 A is commonly used.